How to Prevent Basement Moisture
LESLIE: Now we’ve got Claire in Alaska on the line who’s dealing with a first-time basement. What can we do for you?
CLAIRE: Well, I have purchased a 1900 house and it has this basement that is getting moisture. It has this sticky, black paper on the outside but it is not functioning properly, apparently, because there’s a lot of moisture coming in.
CLAIRE: And it would require digging out on the outside to do the outside. Is there any way to address it from the inside?
TOM: Well, there’s another way to address it on the outside and that is to pay attention to the angle of the soil around the house. So when it does warm up and you have the opportunity to regrade the foundation perimeter and make sure that the angle of the soil, the angle of the grade slopes away from the building.
CLAIRE: I put French drains in all around the property and sloped it and put gravel.
TOM: So there’s – well, OK. Now, if he sloped it with gravel, then he didn’t really do you a favor, because the gravel is porous. So the water goes through the gravel, back to the dirt underneath and into your basement. So if you’re going to slope it – yeah, give him an A for effort but it’s not going to be successful. You have to grade it with clean fill dirt so that you can tamp it and the water will run away from it. Water is not going to run over gravel; it falls through it.
But there’s a second thing to check and that is: do you have gutters on the roof?
CLAIRE: No, because the snow pulled them off.
TOM: Right, OK. Well, look, if you can collect the water at the roof edge – and even if you have deep gutters or if you use the type of gutters that have the warming cables up on the roof, if you prevent water from running off the roof and against that foundation perimeter, you’ll prevent a wet basement, because most of the water collects at the outside.
Protect the perimeter; keep it as dry as possible. And a lot of wet basements are caused because gutters are missing or gutters are clogged and the water rolls off the roof right against the foundation. Soil is flat, so the water has got nowhere to go and it just sits there and leaks into the basement.
CLAIRE: OK. So I’ve got to work on that.
TOM: Good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.